The issue of acidic ferric ions
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In gasoline hydrogenation units, why does the pH value of our acidic solution show an alkaline level of around 8 or 9, yet the iron ion concentration remains relatively high? Can iron ions exist in alkaline solutions?
It probably can’t exist; in alkaline solutions, iron ions form complexes
However, our production department, in order to determine the degree of corrosion on the equipment, requested the laboratory to test the pH value and iron ion content of the acidic water; every time, the pH value was alkaline, and the iron ion content was also high. I’m completely baffled!
What acid is mainly responsible for corrosion?
Corrosion is likely caused by acids, and testing the pH value with pH test strips does not necessarily yield accurate results.
But why is the iron ion content still a bit high?
It is caused by corrosion of carbon steel equipment and pipelines; it is necessary to determine at which stage or process the corrosion occurred, as it may not have arisen at the location where samples were taken
In gasoline hydrogenation units, why does the pH value of our acidic solution show an alkaline level of around 8 or 9, yet the iron ion concentration remains relatively high? Can iron ions exist in alkaline solutions? Could you explain which stream in the hydrogenation process has an elevated level of iron ions, what the specific value is, and what it should be? I’m not very familiar with the specific processes, as I’m not in the same industry, but I do have some knowledge regarding the removal of iron ions, and I hope that can be helpful to you.
Deionized water is added to the reaction products of hydrorefining before they enter the air cooler, in order to prevent ammonium salt crystals from forming and blocking the pipelines； A slow-release scale inhibitor is added to the top of the stabilizer tower in order to prevent hydrogen sulfide from corroding pipelines and equipment. The workshop conducted tests to assess the degree of corrosion, measuring the pH level of the acidic water as well as the iron ion concentration. However, the test results showed that the pH level was between 8 and 9, while the iron ion concentration was 6 PPM or even higher. The workshop requires the level to be kept below 3 ppm.
Deionized water is added to the reaction products of hydrorefining before they enter the air cooler, in order to prevent ammonium salt crystals from forming and blocking the pipelines； A slow-release scale inhibitor is added to the top of the stabilizer tower in order to prevent hydrogen sulfide from corroding pipelines and equipment. The workshop conducted tests to assess the degree of corrosion, measuring the pH level of the acidic water as well as the iron ion concentration. However, the test results showed that the pH level was between 8 and 9, while the iron ion concentration was 6 PPM or even higher. The workshop requires the level to be kept below 3 ppm.